how to join two files with awk. Post: 302593370

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Top Forums Shell Programming and Scripting how to join two files with awk. Post 302593370 by ken002 on Thursday 26th of January 2012 05:03:40 PM

01-26-2012

ken002

Guest

Quote:

Originally Posted by bartus11

This:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a);  print $1, a[$1]}' file1 file2

is equivalent to this:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a) {};  print $1, a[$1]}' file1 file2

I hope you get my point Smilie

Maybe I got it, but I still confused something.

Code:

if ($1 in a) {};

means it prints the matched records in file2 then

Code:

print $1, a[$1]}

print out all records in files 1 and file2. if this is true. the matched records in file2 should be duplicated, but the output doesn't contains any duplicates.

Thanks again.

---------- Post updated at 05:03 PM ---------- Previous update was at 04:49 PM ----------

Quote:

Originally Posted by bartus11

This:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a);  print $1, a[$1]}' file1 file2

is equivalent to this:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a) {};  print $1, a[$1]}' file1 file2

I hope you get my point Smilie

I got it

Code:

if ($1 in a) {}

means if match found, do nothing.

---------- Post updated at 05:03 PM ---------- Previous update was at 05:03 PM ----------

Quote:

Originally Posted by bartus11

This:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a);  print $1, a[$1]}' file1 file2

is equivalent to this:

Code:

awk 'NR==FNR {a[$1]=$1; next} {if ($1 in a) {};  print $1, a[$1]}' file1 file2

I hope you get my point Smilie

I got it

Code:

if ($1 in a) {}

means if match found, do nothing.

ken002

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